National Heritage Techniques and History and Relevance to Local and District: Characterization of Materials, Quarrying Ornamenta
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Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014 Geological Society, London, Special Publications Online First Ornamental stones of the Verbano Cusio Ossola quarry district: characterization of materials, quarrying techniques and history and relevance to local and national heritage Giovanna A. Dino and Alessandro Cavallo Geological Society, London, Special Publications, first published October 15, 2014; doi 10.1144/SP407.15 Email alerting click here to receive free e-mail alerts when service new articles cite this article Permission click here to seek permission to re-use all or request part of this article Subscribe click here to subscribe to Geological Society, London, Special Publications or the Lyell Collection How to cite click here for further information about Online First and how to cite articles Notes © The Geological Society of London 2014 Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014 Ornamental stones of the Verbano Cusio Ossola quarry district: characterization of materials, quarrying techniques and history and relevance to local and national heritage GIOVANNA A. DINO1 & ALESSANDRO CAVALLO2* 1Earth Sciences Department, University of Turin, Via Valperga Caluso, 35, 10125 Torino (TO), Italy 2Department of Earth and Environmental Sciences, University of Milan-Bicocca, Piazza della Scienza, 4–20126 Milano (MI), Italy *Corresponding author (e-mail: [email protected]) Abstract: This paper reports the results of an Interreg Project (OSMATER – Sub-Alpine Obser- vatory Materials Territory Restoration) that investigated the present and historical quarrying and processing activities in the cross-border area between the Ossola Valley (Italy) and the Canton Ticino (Switzerland), and the use of dimension stones in local and national architecture. These materials are in many ways unique for their abundance and lithological variety. In the past, their extraction, processing and application characterized in a decisive way the architectural and con- structive culture, both in terms of prestigious architecture and civil buildings, establishing a relationship between ‘stones and culture’, and ‘territory and its resources’. In recent years, many traditions of the quarrying, processing and architectural activities are losing importance and inter- est is being loss, resulting in a loss of knowledge and historical memory. The loss of this knowledge is likely to become irreversible in the short term, with the disappearance of people and social groups as depositaries of tradition. We conclude that the creation of an ‘observatory’, like OSMATER, is desirable and, indeed, essential if we want to preserve the historical memory of the stone industry of an entire production area. This paper reports the results of the Interreg and typical of this territory (VCO) and its remark- PIC IIIA Project called OSMATER (Osservatorio able cultural and historical heritage. Sub-Alpino Materiali Territorio Restauro). The specific aim of the OSMATER project is to redis- cover the close relationships among landscape, Geological setting quarry exploitation, culture and local architecture. These relationships were developed both in the The VCO province is one of the most important Verbano-Cusio-Ossola (VCO) area (Piedmont, NW Italian quarrying districts, due to the variety of the Italy) and in the Canton Ticino district (Switzer- exploited rocks (Fig. 1): from granites (e.g. Rosa land). The knowledge and the exploitation of Baveno and Bianco Montorfano) to orthogneisses local materials employed in historical and rural (Beola and Serizzo), marbles (e.g. Candoglia) and buildings are the basis for appreciable local and greenstones (Pietra Laugera). This wealth of build- widespread heritage preservation. The means for ing and ornamental stones is closely linked to the securing useful information was a census and clas- unusual geology of this area (Fig. 2): the thickest sification of rocks, quarries (both active and his- geological section (20 km) of the Alpine belt can torical – since the Roman age), monuments and be found here. This belt is formed by several construction techniques typical of the sub-Alpine nappe systems with subvertical attitude to the S in region, in order to create a documentation centre the median valley and subhorizontal to the N in through a dedicated website. The OSMATER pro- the Antigorio Valley where the deepest units crop ject represents a good chance both for the preser- out. The basement and cover units were metamor- vation of local buildings and quarries. Also, by phosed during the Alpine event under amphibolite means of VCO geo-tourism routes ‘from quarry to facies conditions. building’, there is a really important chance to From S to N, the VCO district shows two impor- improve and revitalise the tourist sector of the area tant structural domains separated by the Periadri- and to enhance understanding of the peculiarity atic lineament, here known as Canavese Line. of materials, exploitation and working techniques, These are the prealpine crystalline basement of and architectural applications, which are unique the Southern Alps (Africa-verging belt) and the From:Pereira, D., Marker, B. R., Kramar, S., Cooper,B.J.&Schouenborg, B. E. (eds) Global Heritage Stone: Towards International Recognition of Building and Ornamental Stones. Geological Society, London, Special Publications, 407, http://dx.doi.org/10.1144/SP407.15 # The Geological Society of London 2014. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014 G. A. DINO & A. CAVALLO Fig. 1. Main ornamental stones from the VCO area: (a) Rosa Baveno granite; (b) Bianco Montorfano granite; (c) Verde Mergozzo granite; (d) Candoglia marble; (e) Grigio Boden marble; (f) Palissandro Bluette marble; (g) Palissandro Blu Nuvolato marble; (h) Palissandro Oniciato marble; (i) Palissandro Classico marble; (j) Serizzo Antigorio gneiss; (k) Serizzo Sempione gneiss; (l) Serizzo Monte Rosa gneiss; (m) Serizzo Formazza gneiss; (n) Quarzite Bianca gneiss; (o) Verde Vogogna gneiss; (p) Beola Bianca gneiss; (q) Beola Favalle gneiss; (r) Beola Ghiandonata gneiss; (s) Beola Grigia gneiss; (t) Beola Isorno gneiss. Alpine nappe systems of the Europe-verging belt. 280 My, the so-called Graniti dei Laghi) and dykes For detailed studies of this area, see Schmid et al. or stocks of the Appinite suite intrude this base- (1987), Colombo & Tunesi (1999), Boriani (2000), ment. The granites were extensively quarried in Engi et al. (2001), Boriani & Giobbi (2004), the past (Baveno, Montorfano, Alzo, Roccapietra Keller et al. (2005), Maxelon & Mancktelow (2005), and Quarna). Colombo & Cavallo (2007), Pleuger et al. (2007) The Ivrea-Verbano Zone consists of two main and references therein. units: the Kinzigite Formation and the Mafic Com- The basement of the Southern Alps includes: plex, which underwent upper-amphibolite to granu- the Serie dei Laghi (upper continental crust) to the lite facies conditions. The Kinzigite Formation is SE and the Ivrea-Verbano Zone (lower continen- a volcano-sedimentary sequence, constituted of tal crust) to the NW, divided by the subvertical prevailing metapelites, metapsammites, marbles Cossato-Mergozzo-Brissago Line. The Serie dei and quartzites with interlayered metabasites and Laghi is comprised of the metapelitic Scisti dei lenses of ultramafites (spinel lherzolites), mainly Laghi and the metapsammitic Strona-Ceneri Zone: occurring near the Canavese Line. During the Early the contact is represented by banded amphibolites, Permian this sequence was intruded by a layered lenses of ultramafites and metagabbros (Strona Cen- Mafic Complex (peridotites, pyroxenites, gabbro- eri Border Zone). Late Variscan granites (around norites and anorthosites) and a huge body of quite Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014 VERBANO CUSIO OSSOLA DISTRICT STONES Fig. 2. Geological sketch-map of the VCO area. homogeneous amphibole-bearing gabbro (Main marbles) and a granulitic amphibole-bearing gab- Gabbro). The Mafic Complex shows granulite facies bro (Gabbro di Anzola). assemblages. The present tectonic setting of this The Alpine nappe system occurs from the middle Zone is possibly due to an early Permian trans- Ossola Valley across the border into Switzerland. tensional emplacement of the Ivrea-Verbano Zone The nappes consist of minor Permo-Mesozoic near the Serie dei Laghi (Boriani & Giobbi 2004). cover rocks and widespread pre-alpine crystal- In the Ossola Valley, rocks of the Ivrea-Verbano line basement intruded by late-Variscan gabbroic Zone are quarried to extract marbles from the and granitoid plutons. Strong Alpine metamorphic Kinzigite Formation (Candoglia and Ornavasso overprinting was mainly of amphibolite facies Downloaded from http://sp.lyellcollection.org/ at Universita Di Milano Bicocca on October 16, 2014 G. A. DINO & A. CAVALLO condtions. Relicts of the pre-alpine or eo-alpine conditions of Alpine age. The orthogneisses history are scarce and mainly recognized in the Aus- within the Moncucco-Orselina-Isorno Zone troalpine units, Piemontese Zone and Upper Penni- are late-Variscan granites, which were meta- nic nappes (Monte Rosa). The granitoids occur both morphosed during the alpine event (Keller in the Austroalpine and Penninic basements while et al. 2005). Most varieties of Beola Stone the gabbros are absent from the basement